A punch press provides the speed, but is it flexible enough? A laser provides high-quality cuts, but will it be able to keep up with high-volume cutting job that make so much sense for a punch press? Does a punch/sheer or a punch/laser machine make sense, or would you be better off with two stand-alone machines?

According to Ingo Bentrup of Advanced Sheetmetal Technologies, these are questions that must be thoroughly researched, answered, and tested before purchasing.

"But matching technology to individual fabricating needs is never simple. However, there are some basic guidelines might help you decide if a punch press, a laser, or a combination machine will be best for working with 2-D sheet metal," says Bentrup.

The machine choices for punching or laser cutting could include any of the following:

• Turret punch press with either hydraulic or servo-electric punching system.

• Flying-optic laser with either AC digital servo or linear drives.

• Punch/shear combination machines with AC digital servo or linear drives.

• Laser/punch combination machines with hydraulic or servo-electric punching systems with either AC digital servo or linear drives.

Bentrup says to obtain maximum productivity there are many factors that need to be considered, including:

Is the new machine a stopgap just to add more capacity? How will operator comfort be with existing equipment and software? Do you want better parts quality? Will low- or high-volume parts be produced? Are you out to reduce work-in-process and labour costs? Are you looking to combine several existing manufacturing steps into one?

Today’s turret press offers a great deal of flexibility to sheet metal fabricators.

For example, if you need a machine to provide fast contouring and forming in a variety of materials – including aluminum, stainless steel, cold-rolled steel, and Lexan – with thickness from 1.5mm to 8.0mm. a turret punch is a good choice.

If tool marks on parts are not a concern and the parts do not have many contours, a turret punch, coupled with efficient programming software, often is the best and most economical choice.

When precision forming is required, the high precision of a servo-electric turret press is noteworthy. The precise upper and lower ram movements help to create special flanges and forms, thus reducing the need for secondary operations. However, servo-electric turret punch presses do not offer the tonnage capacity or the speed of their hydraulic counterparts.

For a hydraulic turret punch, the costs of operation include tooling, electricity, labor, and floor space. Maintenance typically involves oil changes, filters, and normal wear and tear caused by tooling. For a servo-electric turret punch, energy costs are considerably lower. No hydraulic oil maintenance is needed, but mechanical drives and wear items require maintenance.

A flying optics laser often is chosen when part quality, not process time, is the paramount concern, along with many complex parts with many curves and small features.

Programming is minimal because the laser is the only tool and it doesn’t perform any forming sequences. Production software, which enables setup of multiple jobs, is built into the machine. Depending on part and sheet size, nesting capacity can be very high, and sheet distortion generally is minimal.

The type and thickness of material to be cut determine gas use. Operator training and setup skills required are of medium to high complexity. Cutting time depends on the power of the laser and on the X/Y drive system stability, which allows for high accelerations.

For a laser include lenses, tips and cutting; and laser gases such as nitrogen, oxygen, and helium in varying grades and costs. Longer-term expenses include replacement of turbines, resonators, and major service maintenance checks on the laser optics.

The purpose of the punch/shear machine design is to provide one machine capable of transforming a full-sized sheet into finished parts ready for the next operation in a single, unattended step. These parts can be moved to final production stages for immediate integration directly into final product assembly.

Material usage is improved with versatile nesting programs. As loading, punching, shearing, and unloading of individual parts become automated, scrap and costs associated with manual labour are reduced. The level of automation can be customised through flexible, modular systems for raw material storage, loading, unloading, part sorting and stacking.

Tool marks on parts are minimised where the shear is used to cut external contours. The combination turret punch press/right-angle shear, coupled with programming software, is often the best and most economical choice for high-volume parts.

Yet the ability of this machine to sort parts with no tab marks or skeletons makes it a contender for even low-volume jobs, particularly large parts up to 4mm thickness. The machine’s flexibility allows it to be used not only as a punch shear, but also as a ‘punch only’ or a ‘shear only’ if required.

A large tool capacity, as well as automated production software, minimise setup even when both the material type and thickness being queued up are changed. Automated programming systems allow for multiple part nesting and the simple application of specialised tooling for upforming up to 16mm high.

For a punch/shear combination, costs include electricity, tooling and shear blades. Labour costs are reduced because manual operations are such as loading, unloading, and scrap removal are eliminated.

A laser/punch combination integrates punching, forming, tapping, and laser cutting in a single unit for varied sheet metalworking operations. With a laser/punch machine, complete isolation of the laser from the punch provides for vibration-free, accurate laser cutting. As the sheet is moved under the laser, rather then remaining stationary, laser cutting speeds tend to be slower unless higher axis drive speed options, such as linear drives, are used.

A laser/punch combination machine can load material automatically and sort finished parts with a minimum of operator intervention. Production control software built into the machine controls allows for remote setup of work in queues. The programming software allows for multiple part nests on large sheets and supports the use of special form tooling.

Costs includes tooling, high electricity use, (because the laser must be kept live even when not cutting), labor, floor space, lenses, tips, and cutting and laser gases in varying grades and costs. Long-term expenses include replacement of turbines and resonators and longer-term service checks on the laser.